Brachytherapy, also known as “internal radiotherapy”, is a treatment based on radiation administration, used above all for arresting tumour cell multiplication.
The treatment is based on the depositing of radioactive sources—typically in the form of one or more so-called “seeds”—directly in tumour tissue or in that surrounding the tumour growth. The implanted radioactive seed releases a radiation dose uninterruptedly, during a short period of time in the case of temporary implants, or for the entire effective life-time, to a decay, in case of permanent implants.
Currently, two typologies of brachytherapic treatment are practiced, i.e.:                intracavitary treatments, in which the sources are placed in body cavities close to the tumour volume; and        interstitial treatments, in which the sources are implanted within the tumour volume.        
However, generally the brachytherapic treatments currently adopted, and the associated instruments, provide extremely invasive procedures for the depositing in situ of the sources and cannot be applied—or can be in a very limited manner only—to bone tumours, e.g. those of the vertebral column. In particular, some specific body districts, and among these the vertebral bodies, are today hardly accessible or completely inaccessible with available instruments.
Also due to such difficulties, currently the radiotherapy of bone tumours in general, and of those of the vertebral column in particular, is typically performed with radiation therapy administrations from the outside.
Said external radiotherapy, however performed—for instance with a linear accelerator (LINAC), with intensity-modulated radiation therapy (IMRT), that is, collimated beams that reach the tumour, with image-guided radiation therapy (IGRT), or, again, with tomotherapy, which is a form of radiation therapy that uses TC to treat the tumour—has to pass through healthy tissues that, in many cases, are subjected to the same radiation as tumour tissues (in the best of hypotheses at a lower dose in the above-mentioned collimated-beam mode).
Moreover, an external radiation therapy treatment is generally administered in a daily single-dose for a sequence of several weeks to reach the optimum therapeutic dose, in an attempt to minimize damages to healthy tissues and increase the probability that tumour cells be exposed to radiations at a stage in which they appear sensitive to DNA damaging. However, this makes the treatment lengthy, costly and physically stressful for the patient.
US 2010/0234669 discloses a brachytherapy application for the treatment of bone tumours based on a cannula that is inserted in the body district of interest and through which radioactive elements are introduced.